This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. (1) Hypothesis: Abnormal vessels regrowth is hypothesized as the main reason of recurrence of PWS after laser treatment in patients. We hypothesize angiogenesis pathway plays an important role during this vessel regrowth, thus inhibition of angiogenesis pathway may result in an improved prognosis. (2) Experimental design: Hamster or mouse animal model will be used for this project. The animal skins will be radiated by laser. The skin tissues before and after laser treatment will be collected, fixed, and sectioned. Some key angiogenesis pathway molecules, including VEGF, mTOR, Akt, PI3K, MAPK etc will be investigated by fluorescent immunohistochemistry. (3) After we establish a solid data from animal model, we will perform similar experiments in human skin. Briefly, normal and PWS human skin will be collected by Dr. Nelson with patients'consents. The skin tissues (around 1mmx1mm) will be fixed immediately for overnight and sectioned. The key molecules involving in angiogenesis will be investigated by fluorescent immunohistochemistry. (4) Two fluorophores will be used: 488 and 549. Single or double staining will be performed simultaneously.